Building on an existing Californian law which requires all new buildings to leave at least 15% of their roof exposed to sunshine for future solar upgrades, San Francisco has just become the first big city in the state to require ALL new builds, 10-storys or less, to be fitted with rooftop solar panels. This landmark legislation was unanimously passed by the City of San Francisco’s Board of Supervisors this week and, luckily, San Francisco is blessed with around 260 days of sunshine annually.

Starting in January 2017, any new building of 10 or less floors must integrate either solar PV or solar thermal panels as the threat of climate change rises to the tops of City Hall agendas across California and beyond. Other smaller Californian cities already have similar legislature in place, but San Francisco is the first big metropolis in the state to adopt these measures. “In a dense, urban environment, we need to be smart and efficient about how we maximize the use of our space to achieve goals such as promoting renewable energy and improving our environment,” said Supervisor Scott Wiener in a statement to the press.

Weiner, who is the official responsible for proposing this new rule, also has big plans for “living roofs” by turning them into urban gardens which can provide cheap and sustainable insulation for a building, as well as tackling pollution and creating new habitats for wildlife in the city. “This legislation will activate our roofs, which are an under-utilized urban resource, to make our city more sustainable and our air cleaner,” he explained.

The move comes as San Francisco continues on its path to use 100% renewable energy for electricity by 2020 so it comes as no surprise that the city and its neighbouring Silicon Valley are seeing an upsurge of startups and investments in environmental technology and engineering.